Provided is an absorption heat pump device that can suppress decreased absorption heat pump device performance resulting from improper control of the concentration of an absorbing liquid due to a vehicle body tilting and swaying when the device is mounted on a vehicle. An absorption heat pump device (100) in which refrigerant vapor is absorbed by an absorbing liquid comprises: an evaporator (30) that causes a refrigerant to evaporate; and an absorber (40) that causes the refrigerant vapor generated with the evaporator to be absorbed into the absorbing liquid. The absorber includes: a heat exchanging unit (42) that removes the heat of absorption from the refrigerant vapor absorbed into the absorbing liquid; and a membrane member (45) that is formed such that the refrigerant vapor can penetrate without allowing the absorbing liquid to penetrate, and that is disposed so as to enclose and cover the heat exchanger unit with which the absorbing liquid comes into contact.